1. Field of the Invention
The present invention relates to a drawing apparatus, and a method of manufacturing an article.
2. Description of the Related Art
Along with the higher integration and miniaturization of semiconductor devices, a drawing apparatus using a charged particle beam (electron beam) and an EUV exposure apparatus using EUV (extreme ultraviolet) rays have been developed as a lithography apparatus of the next generation, which forms (transfers) a pattern on a substrate.
For example, in the EUV exposure apparatus, a technique of removing contaminations such as carbon films deposited on a mirror (reflective optical member) has been proposed by Japanese Patent Laid-Open Nos. 2011-86885 and 2011-86886. With the technique of Japanese Patent Laid-Open Nos. 2011-86885 and 2011-86886, active species (ozonide) are generated by mixing unsaturated hydrocarbon and ozone, and contaminations are removed by such active species.
In the drawing apparatus as well, contaminations are deposited on a member having an aperture through which charged particle beam passes (for example, an electrostatic lens or aperture) due to outgases emitted from a substrate and a resist applied on the substrate, and secondary electrons generated when a charged particle beam strikes the substrate. Especially, the contamination deposited in the vicinity of the aperture of such member influences an orbit of the charged particle beam which passes through the aperture when it is charged (that is, the charged particle beam is deviated from a target orbit). Since the contamination is deposited, the aperture size of the electrostatic lens or aperture is reduced, and an intensity (current) of the charged particle beam which passes through the aperture is decreased, resulting in a throughput drop. Alternatively, since the contamination is deposited, the roundness of the aperture of the electrostatic lens is changed, thus generating aberrations.
Hence, the technique of Japanese Patent Laid-Open Nos. 2011-86885 and 2011-86886 may be applied to a drawing apparatus. However, when active species are separated away from positions where they are generated by reaction between unsaturated hydrocarbon and ozone, they are abruptly deactivated (contamination removing efficiency lowers). Therefore, contaminations deposited in the vicinity of the aperture of the electrostatic lens or aperture cannot be sufficiently removed.